Preheat the oven to 180°C, fan 160°C, gas 4 and line a baking tray with nonstick baking paper.
Halve the marzipan and roll each piece into a smooth stick about 20cm in length.
In a bowl, beat the caster sugar and quark or cottage cheese together until smooth, then beat in the melted butter, egg, ground almonds, extracts and mixed spice.
Sift the flour and baking powder over the cheese mixture and stir through evenly. Add the dried fruit and stir again. The texture will be like a soft scone dough.
Lightly flour a work surface and shape half of the dough mixture into a 20cm long log. Press one stick of marzipan into the dough lengthways, then pinch the dough up and around to seal it inside. Move the log carefully to the tray using a spatula, then do the same with the remaining dough and marzipan, making sure they are spaced well apart on the baking tray.
Bake for about 45 minutes until risen, slightly firm and golden. Remove from the oven, leave to cool for 10 minutes, then brush with extra melted butter and leave to cool completely. When cold, dredge with icing sugar. Wrap well in cling film or baking paper and store in an airtight container for up to one week.